Diffs outputs are strange if the Pretty print differences setting is turned on

[pavel-krivanek]

If the "Pretty print differences" setting is turned on, the outputs of diff comparisons provide confusing output

For example, the first yellow bar marks a modification but not user cannot see what changed. And sometimes, it can get really wild

I think that Calypso sets this setting globally when it is set in one of the diff window in the browser so it is not that special case.